Synaptic Transmission Muscular

Question 1

Step 1

Answer 1

Action potential arrives at the end of the axon (axon terminal)

Question 2

Step 2

Answer 2

Calcium channels open and calcium ions rush into the axon terminal

Question 3

Step 3

Answer 3

Calcium ions interact with vesicles (containing a neurotransmitter) stored in the axon terminal, causing them to migrate to and fuse w the membrane of the axon terminal

Question 4

Step 4

Answer 4

The neurotransmitter involved in the travel of the electrical impulse from a neuron to muscle fiber is acetylcholine (Ach). Ach is a neurotransmitter made by combining choline and an acetyl group. Ach is typically released by presynaptic neurons at neuromuscular junctions in order to trigger muscle contraction.

Question 5

Step 5

Answer 5

It triggers the contractions by binding to receptors (cholinergic/nicotinic) in the membrane of the postsynaptic muscle fibers. This allows Na+ ions to diffuse into postsynaptic muscle fiber cells.

Question 6

Step 6

Answer 6

Acetylcholinesterase is released by the presynaptic cells and the enzyme continuously breaks Ach down into choline and an acetyl group. Choline is taken back into the presynaptic cell to be used to make Ach again.

Question 7

Step 7

Answer 7

The binding of Ach causes ion channels to open, changing their 3o structure. Na+ ions rush into the postsynaptic cell causing depolarization (excitatory) or Cl- ions rush into the postsynaptic cell resulting in hyperpolarization (inhibitory).

Question 8

Step 8

Answer 8

Acetylcholinesterase breaks down Ach into two or more fragments. The ion channels then close on the postsynaptic membrane and their pieces diffuse back into presynaptic neurons to be assembled into vesicles again.